Study of zirconia surface modification by femto-second laser.

为了提高氧化锆义齿的粘接强度，我们采用飞秒激光对氧化锆义齿进行表面改性。在这项研究中，两个线性微槽的排列采用的表面上。考察了粘接剪切强度的增加情况以及取向对强度的影响。采用飞秒激光系统对直径为5 mm的全烧结氧化锆圆棒端面进行了加工，激光脉冲能量为9μJ，光斑进给量为5 μm/pulse。通过该工艺，获得了深51μm、宽53μm的微槽。在这项研究中，两种类型的线性凹槽的对齐。在第一次对准中，直的凹槽线是平行的。将改性的氧化锆表面结合到Crearfil DC Core Auto-mix ONE（Kuraray Medical Inc.，日本），载玻片的表面被转移到该载玻片上。使用的粘合剂是Crearfil SA Cement Auto-mix universal（Kuraray Medical Inc.，日本）。厚度为50μm，圆形结合区直径为4 mm。在万能试验机（DCS-5000，Shimazu Co.）上进行粘合剪切强度试验，其中十字头的速度为1 mm/min。具有直线平行微槽的氧化锆表面的粘附剪切强度为35.8（S.D.：6.0)MPa，而无凹槽的原始表面的强度为23.4（S.D.：9.2)MPa.此外，具有十字型微槽的表面的强度增加到46.8（S.D.：5.5)MPa.飞秒激光表面改性技术是提高氧化锆假体与骨水泥结合强度的有效手段。

We modified the surface of zirconia dental prostheses through femto-second laser process in order to improve the adhesion strength of them. In this study, two alignments of linear micro-grooves were employed on the surface. The increase of adhesion shear strength and the effect of the alignment on the strength were examined. A round end surface of a fully-sintered zirconia bar with diameter of 5mm was processed with femto-second laser system, which provided pulse energy of 9μJ and spot feed of5μm/pulse. Through the process, micro grooves with depth of 51μm and width of 53μm were obtained. In this study, two types of alignments in linear grooves were produced. In the first alignment, straight groove lines were parallel. In the second, two groups of parallel grooves were perpendicular to each other.The modified zirconia surfaces were bonded to the mirror surface of Crearfil DC Core Auto-mix ONE (Kuraray Medical Inc.,Japan) to which the surface of a glass slide was transferred. The adhesion used was Crearfil SA Cement Auto-mix universal (Kuraray Medical Inc.,Japan). The thickness was 50μm and the diameter of round bonded area was 4mm. Adhesion shear strength tests were carriedout on the universal testing machine(DCS-5000, Shimazu Co.), in which the speed of cross head was 1mm/min.The adhesion shear strength of zirconia surface with linear parallel microgrooves was35.8(S.D.:6.0) MPa, while the strength of original surface without grooves was23.4(S.D.:9.2) MPa. Moreover, the strength of the surface with cross-typed microgrooves increased up to 46.8(S.D.:5.5) MPa. The surface modification through femto-second laser process, in which micro-grooves were formed on it, is very useful tool for improving the adhesion strength between zirconia prostheses and cements.